1. Field of the Invention
This invention relates to a device for correcting a tremble of a focused image of an object caused by an oscillation of an optical device due to, for example, a hand tremble.
2. Description of the Related Art
Usually, an optical device is provided with a device for correcting a tremble of an focused image. The device for correcting the tremble includes a sensor of angular speed, and a correcting optical system which is placed on an optical path of a photographing optical system of the optical device. An amount of trembling of the optical device is calculated by integrating a signal output from the sensor of angular speed. The correcting optical system is driven so that the tremble of the focused image, caused by an oscillation of the optical device, is canceled.
Accordingly, a movement of an object image on, for example, a surface of a camera film and a light receiving surface of photoelectric conversion element is corrected. Namely, the focused image tremble of the object is corrected. Usually, the correction of the focused image tremble is carried out during the exposure period. However, if a single lens reflex camera, in which a finder optical system includes a photographing optical system, is provided with the device for correcting the focused image tremble, the correction of the focused image tremble is carried out during a photometry period. During the photometry period, a user views the object through a finder.
However, during the photometry period, the camera is often panned widely in one direction for deciding on or changing a composition, causing a focused image tremble larger than that due to a hand tremble. Namely, the focused image tremble, beyond a range in which the focused image tremble is able to be corrected by the correction optical system, may occur during the photometry period. If the focused image tremble exceeds the range, the correction of the focused image tremble is stopped till the focused image tremble is restored to the range. Accordingly, a problem occurs in which the focused image tremble due to the hand tremble is not sufficiently corrected, just after the camera is panned.
Therefore, an object of the present invention is to provide a device for correcting the focused image tremble, which can restart its control in a short time, after a large focused image tremble, which is unable to be corrected, occurs. Another object of the present invention is to provide a camera, provided with the correcting device.
In accordance with an aspect of the present invention, there is provided a device for correcting a tremble of a focused image comprising: a tremble detector that detects a tremble of optical axes of an optical device; correction optical systems that correct the tremble of the optical axes; driving devices that drive the correction optical systems; a controlling system that controls the driving devices such that the correction optical systems are driven following the tremble of the optical axes in order to cancel a focused image tremble of an object due to the tremble of the optical axes.
The controlling system controls the driving devices such that: when the tremble of the optical axes becomes beyond a correctable range of the correction optical systems, the correction optical systems are stopped from being driven following the tremble of the optical axes; and when a direction of the tremble of the optical axes is reversed in a situation that the tremble of the optical axes is out of the correctable range, the correction optical systems are restarted, after having been stopped, to be driven following the tremble of the optical axes.
The controlling system controls the driving devices, such that from a time after which the tremble of the optical axes becomes beyond the correctable range till a time at which the direction of the tremble of the optical axes is reversed, the correction optical systems approach a standard position by a predetermined time constant. The optical axes of the correction optical systems are coaxial with optical axes of other optical systems of imaging optical systems of the optical device at the standard position.
The predetermined time constant is set such that the correction optical systems reach the standard position from a boundary position of the correctable range in approximately 5 seconds.
When the tremble of the optical axes becomes beyond the correctable range, the correction optical systems are not driven. Then when the direction of the tremble of the optical axes is reversed, the controlling system starts the correction optical systems. Further, the controlling system stops the correction optical systems at positions at which the correction optical systems are situated immediately before the tremble of the optical axes becomes beyond the correctable range.
The optical device further comprises: a photographing optical system; and a photographing control system that records an image of the object, controlling an image capturing operation. The controlling system carries out the stop and the restart control of driving the correction optical systems after the tremble of the optical axes becomes beyond the correctable range, only when the image capturing operation is not carried out.
In accordance with another aspect of the present invention, there is provided a camera which is provided with a device for correcting a tremble of a focused image comprising: a photographing optical system; tremble detectors that detect a tremble of an Optical axis of the photographing optical system; a correction optical system that corrects the tremble of the optical axis, being provided for the tremble correcting device so as to be included in the photographing optical system; a driving device that drives the correction optical system; a photographing controlling system that records an image of the object, controlling an image capturing operation; and a tremble correction controlling system that controls the driving device such that the correction optical system is driven following the tremble of the optical axis in order to cancel a focused image tremble of an object due to the tremble of the optical axis. The tremble correction controlling system controls the driving device such that: when the tremble of the optical axis becomes beyond a correctable range of the correction optical system, the correction optical system is stopped from being driven following the tremble of the optical axis; and when a direction of the tremble of the optical axis is reversed in a situation that the tremble of the optical axis is out of the correctable range, the correction optical system is restarted to be driven following the tremble of the optical axis.
The tremble correction controlling system controls the driving device, such that from a time after which the tremble of the optical axis becomes beyond the correctable range till a time at which the direction of the tremble of said optical axis is reversed, said correction optical system approaches a standard position by a predetermined time constant, an optical axis of the correction optical system being coaxial with optical axes of other optical systems of the photographing optical system at the standard position.
The predetermined time constant is set such that the correction optical system reaches the standard position from a boundary position of the correctable range in approximately 5 seconds.
When at a time after the focused image tremble becomes beyond the correctable range, the correction optical system is not driven. Then when the direction of the tremble of the optical axis is reversed, the controlling system starts the correction optical system. Further, the controlling system stops the correction optical system at a position at which the correction optical system is situated immediately before the tremble of the optical axis of the photographing optical system becomes beyond the correctable range.